Fix for 'if' special construct type

If one branch has Nothing type (contains 'return', etc.),
return result type of corresponding resolved call (it may depend on smart casts)
 #KT-6242 Fixed

compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/ControlStructureTypingVisitor.java

@@ -133,21 +133,22 @@ public class ControlStructureTypingVisitor extends ExpressionTypingVisitor {
         boolean jumpInThen = thenType != null && KotlinBuiltIns.getInstance().isNothing(thenType);
         boolean jumpInElse = elseType != null && KotlinBuiltIns.getInstance().isNothing(elseType);
 
-        JetTypeInfo result;
+        DataFlowInfo resultDataFlowInfo;
         if (thenType == null && elseType == null) {
-            result = JetTypeInfo.create(null, thenDataFlowInfo.or(elseDataFlowInfo));
+            resultDataFlowInfo = thenDataFlowInfo.or(elseDataFlowInfo);
         }
         else if (thenType == null || (jumpInThen && !jumpInElse)) {
-            result = elseTypeInfo;
+            resultDataFlowInfo = elseDataFlowInfo;
         }
         else if (elseType == null || (jumpInElse && !jumpInThen)) {
-            result = thenTypeInfo;
+            resultDataFlowInfo = thenDataFlowInfo;
         }
         else {
-            result = JetTypeInfo.create(resolvedCall.getResultingDescriptor().getReturnType(), thenDataFlowInfo.or(elseDataFlowInfo));
+            resultDataFlowInfo = thenDataFlowInfo.or(elseDataFlowInfo);
         }
 
-        return DataFlowUtils.checkImplicitCast(result.getType(), ifExpression, contextWithExpectedType, isStatement, result.getDataFlowInfo());
+        JetType resultType = resolvedCall.getResultingDescriptor().getReturnType();
+        return DataFlowUtils.checkImplicitCast(resultType, ifExpression, contextWithExpectedType, isStatement, resultDataFlowInfo);
     }
 
     @NotNull

compiler/testData/diagnostics/tests/smartCasts/inference/kt6242.kt

@@ -0,0 +1,12 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+inline fun<T> foo(block: () -> T):T = block()
+
+fun baz() {
+    val x: String = foo {
+        val task: String? = null
+        if (task == null) {
+            return
+        } else <!DEBUG_INFO_SMARTCAST!>task<!>
+    }
+}

compiler/testData/diagnostics/tests/smartCasts/inference/kt6242.lazy.log

@@ -0,0 +1,62 @@
+DescriptorResolver@0 {
+    <name not found> = NullValue@1
+}
+
+LazyAnnotationDescriptor@2 {
+    resolutionResults = OverloadResolutionResultsImpl@3
+    type = JetTypeImpl@4['inline']
+    valueArguments(ValueParameterDescriptorImpl@5['strategy']) = null
+}
+
+LazyJavaPackageFragmentProvider@6 {
+    packageFragments('<root>': FqName@7) = LazyJavaPackageFragment@8['<root>']
+    packageFragments('String': FqName@9) = null
+    packageFragments('T': FqName@10) = null
+    packageFragments('inline': FqName@11) = null
+    packageFragments('java': FqName@12) = LazyJavaPackageFragment@13['java']
+    packageFragments('java.lang': FqName@14) = LazyJavaPackageFragment@15['lang']
+    packageFragments('java.lang.String': FqName@16) = null
+    packageFragments('java.lang.T': FqName@17) = null
+    packageFragments('java.lang.inline': FqName@18) = null
+    packageFragments('kotlin': FqName@19) = null
+    packageFragments('kotlin.String': FqName@20) = null
+    packageFragments('kotlin.T': FqName@21) = null
+    packageFragments('kotlin.inline': FqName@22) = null
+    packageFragments('kotlin.io': FqName@23) = null
+    packageFragments('kotlin.jvm': FqName@24) = null
+}
+
+LazyJavaPackageFragment@8['<root>'] {
+    classes('String': Name@25) = null // through LazyPackageFragmentScopeForJavaPackage@26
+    classes('block': Name@27) = null // through LazyPackageFragmentScopeForJavaPackage@26
+    classes('equals': Name@28) = null // through LazyPackageFragmentScopeForJavaPackage@26
+    classes('foo': Name@29) = null // through LazyPackageFragmentScopeForJavaPackage@26
+    classes('inline': Name@30) = null // through LazyPackageFragmentScopeForJavaPackage@26
+    classes('invoke': Name@31) = null // through LazyPackageFragmentScopeForJavaPackage@26
+    deserializedPackageScope = Empty@32 // through LazyPackageFragmentScopeForJavaPackage@26
+    functions('block': Name@27) = EmptyList@33[empty] // through LazyPackageFragmentScopeForJavaPackage@26
+    functions('equals': Name@28) = EmptyList@33[empty] // through LazyPackageFragmentScopeForJavaPackage@26
+    functions('foo': Name@29) = EmptyList@33[empty] // through LazyPackageFragmentScopeForJavaPackage@26
+    functions('invoke': Name@31) = EmptyList@33[empty] // through LazyPackageFragmentScopeForJavaPackage@26
+    memberIndex = computeMemberIndex$1@34 // through LazyPackageFragmentScopeForJavaPackage@26
+}
+
+LazyJavaPackageFragment@13['java'] {
+    classes('lang': Name@35) = null // through LazyPackageFragmentScopeForJavaPackage@36
+    deserializedPackageScope = Empty@32 // through LazyPackageFragmentScopeForJavaPackage@36
+    functions('lang': Name@37) = EmptyList@33[empty] // through LazyPackageFragmentScopeForJavaPackage@36
+    memberIndex = computeMemberIndex$1@38 // through LazyPackageFragmentScopeForJavaPackage@36
+}
+
+LazyJavaPackageFragment@15['lang'] {
+    classes('block': Name@27) = null // through LazyPackageFragmentScopeForJavaPackage@39
+    classes('equals': Name@28) = null // through LazyPackageFragmentScopeForJavaPackage@39
+    classes('foo': Name@29) = null // through LazyPackageFragmentScopeForJavaPackage@39
+    classes('invoke': Name@31) = null // through LazyPackageFragmentScopeForJavaPackage@39
+    deserializedPackageScope = Empty@32 // through LazyPackageFragmentScopeForJavaPackage@39
+    functions('block': Name@27) = EmptyList@33[empty] // through LazyPackageFragmentScopeForJavaPackage@39
+    functions('equals': Name@28) = EmptyList@33[empty] // through LazyPackageFragmentScopeForJavaPackage@39
+    functions('foo': Name@29) = EmptyList@33[empty] // through LazyPackageFragmentScopeForJavaPackage@39
+    functions('invoke': Name@31) = EmptyList@33[empty] // through LazyPackageFragmentScopeForJavaPackage@39
+    memberIndex = computeMemberIndex$1@40 // through LazyPackageFragmentScopeForJavaPackage@39
+}

compiler/testData/diagnostics/tests/smartCasts/inference/kt6242.txt

@@ -0,0 +1,4 @@
+package
+
+internal fun baz(): kotlin.Unit
+kotlin.inline() internal fun </*0*/ T> foo(/*0*/ block: () -> T): T

compiler/tests/org/jetbrains/jet/checkers/JetDiagnosticsTestGenerated.java

@@ -9546,6 +9546,12 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                     doTest(fileName);
                 }
 
+                @TestMetadata("kt6242.kt")
+                public void testKt6242() throws Exception {
+                    String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/inference/kt6242.kt");
+                    doTest(fileName);
+                }
+
                 @TestMetadata("smartCastOnReceiver.kt")
                 public void testSmartCastOnReceiver() throws Exception {
                     String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/inference/smartCastOnReceiver.kt");